Abstract

A giant magnetocaloric effect was observed at room temperature in compounds with and 0.01. The Cr dopant reduces (or even eliminates) the large thermal hysteresis of MnAs, while it lowers the first-order transitiontemperature from for MnAs to for . Near the Curie temperature, a magnetic field induces a first-order phase transition from a ferromagnetic hexagonal phase to a paramagnetic orthorhombic phase, leading to a maximum value of of at for a field change for . The study on the system may open an important field in searching proper materials for room-temperature magnetic refrigeration.